The present invention relates to a two-dimensional code recognition processing method, a two-dimensional code recognition processing apparatus, and a storage medium for allowing a computer to execute a two-dimensional code recognition processing program. More particularly, the invention relates to a two-dimensional code recognition processing method, a two-dimensional code recognition processing apparatus, and a storage medium for allowing a computer to execute a two-dimensional code recognition processing program, the method and the apparatus providing efficient and accurate recognition of code data based on image data of a suitably captured two-dimensional code.
The so-called bar code system is used extensively in various industrial fields. The system involves encoding in bars alphanumeric characters representing types and conditions of goods and articles, and typically attaching such codes to the goods and products so that the codes may be scanned later for retrieval of relevant information (e.g., about their types and conditions).
FIG. 20 shows a so-called one-dimensional bar code. In this example, a bar code label 500 is made up of a code part 501 and an ID (identification number) part 502. The code part 501 is a combination of different widths of bars (in black) and bar-to-bar gas (blanks). The ID part 502 indicates a code contained in the code part 501. Specifically, the ID part 502 shows as readable information alphanumeric characters that are coded in the code part 501. This type of one-dimensional bar code 500 is scanned by an optical recognition apparatus called a bar code scanner for recognition.
One way of reading the above-described one-dimensional bar code 500 is by use of a CCD video camera. As more and more bars are arranged to accommodate growing volumes of coded information, however, it becomes increasingly difficult for the video camera to read such one-dimensional bar codes 500 properly.
The difficulty in capturing large amounts of bar-coded information with the video camera is circumvented illustratively by a two-dimensional code system proposed to replace the one-dimensional bar code. As depicted in FIG. 21, various kinds of two-dimensional codes have been proposed, each code comprising a code part 601 and an ID part 602. The code part 601 has a plurality of black square cells arranged two-dimensionally according to predetermined layout rules. The ID part 602 indicates a code that is contained in the code part 601.
Greater quantities of information are represented when the information is coded two-dimensionally than if the one-dimensional-code 500 is used. In other words, it is easier for the video camera to read large quantities of information if the information is coded two-dimensionally rather than one-dimensionally.
The two-dimensional code 600 has one disadvantage. That is, when the video camera picks up an image of a two-dimensional code 600 for code recognition, it is often difficult to distinguish the code from smear, dirt or other distracting images nearby. The result is that code data are often difficult to recognize precisely.
As with the one-dimensional bar code 500, the above-mentioned two-dimensional code 600 has the ID part  601 indicating the code in question in a human-readable format such as that of alphanumeric characters. With the two-dimensional code 600, however, it is impossible to recognize just what the code 600 signifies, to what code system the code 600 may possibly belong, or according to what layout rules the square cells making up the code are arranged two-dimensionally.